TITLE: Twin Otter met and nav data Submitted 30 Oct 2002 Version 1.0 AUTHOR: Haflidi H Jonsson CIRPAS/Naval Postgraduate School 3240 Imjin Road, Hangar 510 Marina Municipal Airport Marina, CA 93933 Tel: 831-384-2776 Fax: 831-384-3277 e-mail: hjonsson@nps.navy.mil 1.0 DATASET OVERVIEW The dataset contains the location, velocity, and attitude of the Twin Otter as reported by GPS systems, as well as measured meteorological state variables. Also in the dataset are some calculated meteorological properties, such as wind, true airspeed, pressure altitude, and water vapor density. The winds are obtained by subtracting the true air velocity vector from the ground velocity vector, and may be rather noisy at low wind speeds. Also, wind droppouts in the files usually are due to dropouts of GPS heading or track. Ambient temperature is corrected for dynamic heating. 2.0 INSTRUMENT OVERVIEW Location, altitude, ground speed, track and UTC time were obtained by use of NovAtel RT-20 GPS system. Heading, pitch and roll angles were obtained by use of 4 antenna Trimble Tans Vector GPS system. Temperature was measured by use of Rosemount E102AL total temperature sensor. Dew Point temperature was measure by use of Edgetech 137-C3 Chilled mirror instrument. Static Pressure and dynamic pressure were measured by use of Setra 270 and Setra 239 transducers, respectively. 3.0 DATA COLLECTION AND PROCESSING Data were logged to the CIRPAS Twin Otter data system, which is based on National Instruments computers and LabView instrument drivers. Both the GPS and the analog data were logged at 10 hz, but desampled to 1hz and merged for these archives. Occasional 1 second gaps or dropouts have been filled by interpolation.